U.S. Pat. No. 3,997,967 discloses a razor assembly having a housing to receive a movable trimming device. This trimming device has a first retracted position corresponding to a non-shaving position and a second extended position, corresponding to a shaving position. The trimming device is actuated by a sliding mechanism operated by a knob. The trimming device also comprises a movable covering flap which closes the opening, the flap being biased to the closed position by a spring mechanism. In this embodiment, the razor head pushes the flap to the open position against the return action of the spring mechanism, and the contact between the razor head and the flap may cause damage to cutting blades.